The swallowing action, in particular, the physical property of the food product and the movements of the oral cavity organs during swallowing, is complicated. Therefore, it is extremely difficult to grasp the phenomenon itself accurately. However, in the fields of medical treatment and nursing, to prevent accidental swallowing and accidental ingestion by an old person and a handicapped person, reductions in risks of accidental swallowing and accidental ingestion have been strived through repetition of various trials and errors. Given that recently there have been accident of choking on konjac jelly, in general food products, it is required to assure safety of a food product using an objective value and index.
Two methods are available for solution of the swallowing phenomenon: a method that directly obtains biological information such as a videofluoroscopic swallowing or a myoelectric potential measurement and a method that indirectly obtains information using, for example, a swallowing robot or a numerical value simulation.
FIG. 13 illustrates exemplary videofluoroscopic swallowing (images taken by X-ray). In the left diagram, liquid 49 is in an oral cavity. In the middle diagram, the liquid 49 partially flows to a throat. In the right diagram, the liquid 49 has been swallowed and disappeared.
FIG. 14 illustrates an exemplary myoelectric potential measurement. Electrodes are attached to a masseter and a suprahyoid muscle group to measure a myoelectric potential waveform. Then, the myoelectric potential waveform is integrated to calculate a muscle activity amount.
Although the method that directly obtains biological information allows grasping a behavior during swallowing accurately, in gathering data under various conditions, there is a disadvantage that a considerable load is taken to an examinee.
Meanwhile, one method of indirectly obtaining the information is to use the swallowing robot (see Non-Patent Literature 1). The swallowing robot is very useful for understanding of simple principle of the swallowing phenomenon. However, a behavior and a structure of each of the oral cavity organs of the robot is not easily changed.
Up to the present, numerical analyses on a behavior of a fluid or a bolus such as a solid material in a living body have been performed. For the fluid, an inside of an analysis target region is separated by a grid referred to as a mesh. Calculations have been performed using a lattice method that analyzes physical quantities (speed, temperature, pressure) at the grid point and the inside of the grid (see Non-Patent Literature 2). In the case of treating the bolus as a semisolid, calculations have been performed using a structural analysis method for machine components such as a finite element method (see Non-Patent Literature 3).